Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

These new findings might help explain the preoccupation men can have toward pornography, scientists added. Shapely hips in women are linked with fertility and overall health. As such, it makes sense evolutionarily speaking that studies across cultures have shown men typically find hourglass figures sexy.

To explore the roots of this behavior, researchers had 14 men, average age 25, rate how attractive they found pictures of the naked derrieres of seven women before and after cosmetic surgery that gave them more shapely hips. These operations did not reduce weight but just redistributed it, by implanting fat harvested from the waists into the buttocks.

Brain scans of the men revealed that seeing post-surgery women activated parts of the brain linked with rewards, including regions associated with responses to drugs and alcohol.

It might not be especially surprising that evolution wired the male brain to find attractive bodies rewarding.

"Hugh Hefner could have told us that by showing us how many zeroes are in his bank account," said researcher Steven Platek, an evolutionary cognitive neuroscientist at Georgia Gwinnett College in Lawrenceville, Georgia. "But there's more to it than buying Playboy, Maxim, or FHM."

For instance, "these findings could help further our understanding pornography addiction and related disorders, such as erectile dysfunction in the absence of pornography," he explained. "These findings could also lend to the scientific inquiry about sexual infidelity."

The scientists also found that changes in a woman's body-mass index or BMI — a common measure of body fat — only really affected brain areas linked to simple visual evaluations of size and shape. This may be evidence that body fat influences judgments of female beauty due more to societal norms than brain wiring.

"The media portrays women as wholly too skinny," Platek said. "It's not just about body fat, or body mass index."

What do women think?

Future research could also investigate the effects that attractive figures have on the female brain.

"It turns out women find similar optimally attractive female bodies as attention-grabbing, albeit for different reasons," Platek said. "Women size up other women in an effort to determine their own relative attractiveness and to maintain mate guarding — or, in other words, keep their mate away from optimally designed females."

These findings should not be construed as saying that men are solely programmed by their biology, nor that "women without optimal design should just hang up their mating towel," Platek added.